Oxygen-curable compositions comprising mercapto-functional compounds are known in the art. For example, U.S. Pat. No. 4,267,296 to Homan discloses oxygen-curable compositions obtained by mixing, substantially in the absence of oxygen, at least one mercapto-functional organosilicon-organic copolymer; a mixture of at least two different types of components selected from the group consisting of at least one organosilicon-organic copolymer, at least one mercapto-functional organic compound, and at least one mercapto-functional organosilicon compound; at least one filler; a catalytic amount of an iron carbonyl catalyst; and a proton donor acid that is compatible with the mixed composition and has a dissociation constant in aqueous solution greater than 10.sup.-5.
U.S. Pat. No. 4,239,674 to Homan et al. teaches oxygen-curable mercaptoorganosiloxane compositions obtained by mixing, substantially in the absence of oxygen, at least one mercapto-functional organosiloxane having an average of at least two mercapto-functional siloxane units per molecule; optionally, a filler; and a catalytic amount of a cobaltocene.
U.S. Pat. No. 4,252,932 to Homan et al. discloses oxygen-curable mercaptoorganosiloxane compositions formed by mixing, substantially in the absence of oxygen, at least one mercapto-functional organosiloxane having an average of at least two mercapto-functional siloxane units per molecule; optionally, at least one filler; and a catalytic amount of a metal carbonyl compound.
Peroxide-curable compositions comprising mercaptoorganopolysiloxanes are also known in the art. For example, U.S. Pat. No. 4,279,792 to Homan et al. teaches compositions prepared by mixing a mercaptoorganopolysiloxane having an average of greater than two mercapto-containing siloxane units per molecule; a stannous salt of carboxylic acid having the formula Sn(OR.sup.1).sub.2 wherein R.sup.1 is a monovalent acyl radical; and optionally, an organic peroxide and/or a filler.
U.S. Pat. No. 4,039,505 to Homan et al. discloses siloxane elastomers containing sulfur prepared by mixing a polydimethylsiloxane consisting essentially of methylvinylsiloxane units; a mercaptoorganopolysiloxane having an average of at least two sulfur containing siloxane units per molecule; an organic peroxide; and, optionally a filler.
However, the prior art does not disclose compositions comprising at least one mercapto-functional organosilicon compound and a cure initiator, which cure uniformly regardless of the amount of oxygen present.